A friend on one of mailing list than I joined ask question about some audio terms. I look for the answer around the Internet, post in on the mailing list and create a copy here. Hope this will help you understand the terms better.

Spectral Balance
Relates to the ability of a speaker system to integrate its direct and reflected sound so that it sounds balanced, smooth, and transparent in a typical listening room. Speed – The apparent rapidity with which a reproducing system responds to steep wavefronts and overall musical pace.

Linearity
Measured from a plot of counts vs. signal over the dynamic range and is expressed as a percentage deviation from a straight line fit.

Ambience
As a general audio term, ambience is the background-sound quality of a listening room, surround processor, and/or recording. The ambience of a recording is what gives it space and a sense of realism. It is the sound of the recording studio itself. The recording engineer often synthetically adds ambience if the recording environment was not enough to do the job naturally.

Tonal Acuracy/Balance
Tonal balance is the art of achieving a balance or neutrality of volume between tones. If one tone or frequency is louder, softer, more apparent than another tone, then you do not have accurate tonal balance.

Pitch
In music, pitch is the perception of the frequency of a note. For example, the A above middle C is nowadays set at (often written as “A = 440 Hz”, and known as concert pitch), although this has not always been the case (see #Historical pitch standards). Pitch is often cited as one of the fundamental aspects of music.

Timbre
The character or quality of a sound that distinguishes one instrument, voice, or other sound source from another.

Grainy
The moderate texturing of reproduced sound. The sonic equivalent of noticeable grain appearing in a photograph.

Airy
Having little or no perceptible weight; so light as to resemble air; “airy gauze curtains”.

Overhang
The continuation of a signal at the output of a device or mixer after the original input signal has faded or to hang across or beyond, as on a building.

Decay
A gradual decrease; as of stored charge or current.

Transient
Any of the non-sustaining, non-periodic frequency components of a sound, usually of brief duration and higher amplitude than the sustaining components, and occurring near the onset of the sound (attack transients).

Sibilance
Sound systems with excessive treble response will over-emphasize the “s” or “ch” sounds and produce a hissing sound.